Difference between DNID and Extension in Asterisk?

I have searched about difference between DNID and Extension. But I couldn't find any explanat开发者_开发问答ion regarding DNID and Extension. So can anyone explain me clearly about DNID and Extension with difference.

Thanks in Advance.

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That's an interesting question. One difference I can see is from within macros where the extension would be different from DNID. For example, you might have dialed 0123456789 but the extension (${EXTEN}) will return 's' within the macro. So, I guess the extension can change while you move around in the dialpan but the DNID will remain throughout.

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Dnid Represents the dialed phone number that led to this server. While the dialed phone number also brings you to the corresponding extension the extension it can change with ivr options, goto routing and a few other ways while the dnid stays the same, (unless a force change)

extensions are chosen and changed while dnid for the most part is static.